Organosiloxanes with SiC-bonded groups and a process for preparing the same

ABSTRACT

This invention relates to organosiloxanes which have SiC-bonded ester groups and contain at least one unit of the general formula: 
     
         ROOCCH.sub.2 CH(COOR)CH.sub.2 CHR&#39;CH.sub.2 Si(CH.sub.3).sub.a O.sub.3-a/2 
    
     in which R represents the same or different monovalent hydrocarbon radicals having from 1 to 12 carbon atoms, which are free of aliphatic unsaturation and which may contain one ether oxygen atom; R&#39; represents hydrogen or a methyl group (CH 3 ) and a is 0, 1 or 2. These organosiloxanes can be prepared by hydrolyzing or co-hydrolyzing silanes of the general formula: 
     
         ROOCCH.sub.2 CH(COOR)CH.sub.2 CHR&#39;CH.sub.2 Si(CH.sub.3).sub.a X.sub.3-a, 
    
     where R, R&#39; and a are the same as above and X represents the same or different hydrolyzable atoms or groups. Also, they may be prepared by the addition of a diester of allyl succinic acid and/or methallyl succinic acid to an organosiloxane containing Si-bonded hydrogen. These new organosiloxanes may be used as lubricants for inorganic and organic fibers, metal surfaces and as hydraulic fluids.

The present invention relates to organopolysiloxanes, and moreparticularly to organopolysiloxanes containing SiC-bonded ester groupsand to a process for preparing the same.

BACKGROUND OF THE INVENTION

Organopolysiloxanes containing ester groups are known in the art. Forexample organopolysiloxanes having SiC-bonded ester groups, processesfor their preparation and utilization are described in U.S. Pat. No.2,723,987 to Speier, U.S. Pat. No. 3,450,736 to De Monterey and U.S.Pat. No. 3,859,321 to Traver. Compared to the organopolysiloxanes havingSiC-bonded ester groups described in these references, theorganopolysiloxanes prepared in accordance with this invention are moreresistant to oxidation.

Therefore, it is an object of this invention to provide certainorganosiloxane esters. Another object of this invention is to providecertain organosiloxanes having SiC-bonded ester groups. Another objectof this invention is to provide organosiloxanes having SiC-bonded groupswhich are resistant to oxidation. Still another object of this inventionis to provide a process for preparing organosiloxanes having SiC-bondedesters. A further object of this invention is to provide novelorganosiloxanes having SiC-bonded groups which may be used as textileand metal lubricants. A still further object of this invention is toprovide novel organosiloxanes having SiC-bonded groups which may be usedas hydraulic fluids.

SUMMARY OF INVENTION

The foregoing objects and others which will become apparent from thefollowing description are accomplished in accordance with thisinvention, generally speaking, by providing organopolysiloxanes havingSiC-bonded ester groups in which the organopolysiloxanes contain atleast one unit of the general formula:

    ROOCCH.sub.2 CH(COOR)CH.sub.2 CHR'CH.sub.2 Si(CH.sub.3).sub.a O.sub.3-a/2,

where R represents the same of different, monovalent hydrocarbonradicals having 1 to 12 carbon atoms which are free of aliphaticunsaturation and which may contain an ether oxygen atom, R' representshydrogen or methyl (CH₃) radical; a is 0, 1 or 2.

DETAILED DESCRIPTION OF THE INVENTION

In the organosiloxanes having SiC-bonded ester groups, the radicalsrepresented by R are alkyl radicals, such as the methyl, ethyl,n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, 4-aminopentyl,2-ethylhexyl, as well as heptyl and dodecyl radicals; cycloalkylradicals such as the cyclohexyl radicals; aryl radicals such as thephenyl radical; alkaryl radicals such as the tolyl radicals and aralkylradicals such as the 3-phenylpropyl radical, and the2,2-dimethyl-3-phenyl-propyl radical.

When R is a methyl, 2,2-dimethylpentyl or 2,2-dimethyl-3-phenylpropylradical, then the organosiloxanes prepared in accordance with thisinvention have a higher viscosity than when the R radical is for examplean n-butyl or 2-methoxy-ethylene radical.

It is preferred that the remaining units in the organosiloxanes preparedin accordance with this invention have the general formula

    R".sub.b SiO.sub.4-b/2,

where R" represents the same or different, monovalent hydrocarbonradicals or halogenated monovalent hydrocarbon radicals having from 1 to10 carbon atoms which are free of aliphatic unsaturation and b is 0, 1,2 or 3.

When the hydrocarbon radicals represented by R in the preceding exampleshave less than 11 carbon atoms, then they also represent examples ofhydrocarbon radicals represented by R". Additional examples ofhydrocarbon radicals represented by R" are the various isomer decylradicals.

Examples of halogenated hydrocarbon radicals represented by R" are the1,1,1-trifluoropropyl radical and o-, m- and p-chlorophenyl radicals.

Because of their availability, it is preferred that at least 50 percentof the R" radicals be methyl radicals.

It is preferred that the organosiloxanes having SiC-bonded ester groupscontain from 2 to 300 silicon atoms per molecule. Furthermore it ispreferred that on the average a total of 1.8 to 3 SiC-bonded organicradicals be present for each silicon atom, in order to insure that theorganosiloxanes of this invention are fluid.

Furthermore this invention relates to a process for preparingorganosiloxanes having SiC-bonded ester groups which comprises reactingesters having aliphatic unsaturation in the the presence of a catalystwhich promotes the addition of Si-bonded hydrogen to an aliphaticmultiple bond in which at least one diester of allylsuccinic acid and/ormethallyl succinic acid is used as an ester having aliphaticunsaturation in the acid moiety. The diester may be represented by thegeneral formula:

    ROOCCH.sub.2 CH(COOR)CH.sub.2 CR'═CH.sub.2

in which R and R' are the same as above.

Diesters of allyl or methallyl succinic acid are well known and may beprepared by a process which comprises reacting alcohols with allyl ormethallyl succinic acid anhydride. These acid anhydrides are readilyavailable, for example by reacting propylene or isobutylene with maleicacid anhydride (See Alder et al., Berichte der Deutschen ChemischenGesellschaft, Vol. 76, 1943, page 44, and Phillips, et al., Journal ofthe American Chemical Society, Vol. 80, 1958, page 3665).

Any organosiloxane having Si-bonded hydrogen which could have been usedheretofore in the addition of Si-bonded hydrogen to organic compoundscontaining at least one unsaturated bond, may be used in this invention.

Examples of organosiloxanes which may be used in the process of thisinvention are 1,1,3,3-tetramethyldisiloxanes and organopolysiloxaneshaving the general formula:

    R".sub.3 Si(OSiR".sub.2).sub.m (OSiHR").sub.298-m OSiR".sub.3,

in which R" is the same as above and m is zero or an integer having avalue of 1 to 297. However, it is also possible to employ cyclicsiloxanes, for example those of the formula (CH₃ SiHO)_(n), where n isan integer having a value of 3 to 6; or branched siloxanes, for examplethose of the general formula

    HSi[OSi(CH.sub.3).sub.3 ].sub.3.

The same catalysts which have been used heretofore to promote theaddition of Si-bonded hydrogen to aliphatically unsaturated bonds may beused in this invention to promote the addition of Si-bonded hydrogen tocompounds containing at least one aliphatically unsaturated bond.Examples of suitable catalysts which may be employed in this invention,are metals such as platinum, ruthenium, rhodium, palladium, iridium andfinely dispersed metals of platinum, ruthenium, rhodium, palladium andiridium. These metals may be applied to carriers such as silicondioxide, aluminum oxide or activated carbon, and compounds or complexesof these elements may be used, such as for example, PtCl₄, PtCl₆.6H₂ O,Na₂ PtCl₄ 4H₂ O, platinum-olefin complexes, platinum-alcohol orplatinum-alcoholate complexes, platinum-ether complexes,platinum-aldehyde complexes, platinum-ketone complexes,platinum-vinylsiloxane complexes, andplatinum-di-vinyltetramethyldisiloxane complexes with or without anydetectable halogen; bis-(gamma-picoline)-platinum dichloride,trimethylene dipyridin-platinum dichloride, as well as iron, nickel andcobalt carbonyls.

When metallic platinum, platinum compounds and/or platinum complexesand/or metallic rhodium are used to promote the addition of Si-bondedhydrogen to an aliphatically unsaturated bond, then these catalysts arepreferably used in amounts of from 0.001 to 0.02 percent by weight pergram atom of Si-bonded hydrogen.

It is preferred that allyl and/or methallyl succinic acid esters beemployed in excess.

The temperatures used in the process of this invention are not criticaland may range from about 18° to 180° C., preferably in the range of from80° to 160° C. and more preferably between 110° and 130° C. The processis generally carried out at atmospheric pressure, but if desired,pressures higher or lower than 1 bar or approximately 1 bar may be used.

Although the process of this invention may be conducted in the absenceof solvents, when solvents are employed, they may be the same solventsas have been used heretofore in processes for the addition of Si-bondedhydrogen to compounds containing at least one aliphatically unsaturatedbond. Moreover, these solvents should be relatively inert to thereactants and the catalysts used in the reaction. Examples of suitablesolvents are alkane mixtures which boil between 80° and 110° C. at 1bar, benzene, toluene and xylene, halogenated alkanes having from 1 to 6carbon atoms, such as methylene chloride, trichloroethylene andperchloroethylene; ethers such as di-n-butyl ether; esters such as ethylacetate and ketones, such as methyl ethyl ketone and cyclohexanone.

When organic solvents are used they are preferably used in an amount offrom 50 to 400 percent by weight based on the weight of theorganosiloxane having Si-bonded hydrogen.

When an excess of the diesters of allyl succinic acids are reacted withthe organosiloxanes containing Si-bonded hydrogen, the excess unreactedester can be recovered by distillation and after further purification,by for example fractional distillation, it can be used in the reactionwith the organosiloxane containing Si-bonded hydrogen.

The organosiloxanes of this invention can also be prepared from thehydrolysis of silanes of the general formula

    ROOCCH.sub.2 CH(COOR)CH.sub.2 CHR'CH.sub.2 Si(CH.sub.3).sub.a X.sub.3-a,

where R, R' and a are the same as above, and X represents the same ordifferent hydrolyzable atoms or groups, such as chlorine atoms, methoxyor ethoxy groups. These silanes may also be mixed with other silaneshaving the general formula:

    R".sub.b SiX.sub.4-b,

where R", b and X are the same as above. Silanes of the general formula:

    ROOCCH.sub.2 CH(COOR)CH.sub.2 CHR'CH.sub.2 Si(CH.sub.3).sub.a X.sub.3-a

may be obtained, for example from the addition of at least one diesterof the general formula:

    ROOCCH.sub.2 CH(COOR)CH.sub.2 CR'═CH.sub.2,

where R and R' are the same as above, to at least one silane of thegeneral formula:

    HSi(CH.sub.3).sub.a X.sub.3-a,

where X and a are the same as above, in the presence of a catalyst whichpromotes the addition of Si-bonded hydrogen to an aliphatic multiplebond. If the ester groups are saponified during this hydrolysis, thenthe carboxyl groups released can again be esterified.

An example of a suitable diester which may be reacted with a silane suchas a trichlorosilane is allyl succinic acid di-n-butyl ester.

The organosiloxanes prepared in accordance with this invention may beused as lubricants for inorganic or organic fibers and as lubricants formetal fabrication and as hydraulic fluids.

Organic fibers that may be treated with the organosiloxanes of thisinvention are natural fibers, for example, wool, cotton, rayon, hemp orsilk, or synthetic fibers, for example, those of polypropylene,polyethylene, polyester, polyurethanes, polyamines, cellulose acetate orpolyacrylonitrile, as well as mixtures of two or more of such materials.The fibres are preferably in the form of single threads or yarns or ofmultiple, mostly treble, twisted threads or yarns. The fibres may,however be in the form of untwisted threads, fleeces, mats, or woven orknitted textiles, including articles of clothing.

The organosiloxanes may be applied to the fibres in any suitable mannerknown in the art, such as by spraying, immersing, roll coating, or bypassing the fibres over a support impregnated with the organosiloxanes.

Through the addition of thickening agents, the organosiloxanes of thisinvention can be converted into greases. Examples of suitable thickeningagents are polytetrafluoroethylene, polyureas, phthalocyanines, clays,silicon dioxides having a BET surface area of at least 50 m² /g andmetallic soaps such as lithium stearate, lithium-12-hydroxystearate,aluminum palmitate and calcium stearate.

The organosiloxanes prepared in accordance with this invention can bemixed with other substances which are generally used in the preparationof lubricants, such as pure organic esters, e.g., carboxylic acid estersof trimethylolpropane or pentaerythritol or antioxidants.

EXAMPLE 1

In a two-liter, four-necked flask which is equipped with a stirrer, anaddition funnel, a reflux condenser and a thermometer, 1025 g of allylsuccinic acid di-n-butyl ester are mixed with 0.5 liters of toluene and40 mg of trimethylene platinum dipyridine-di-chloride and heated to 130°C. After the mixture has been heated, 200 g of a trimethylsiloxyend-blocked methylhydrogenpolysiloxane having on the average 17methylhydrogensiloxane units per molecule, is added dropwise withconstant stirring. During the addition, the temperature is maintained at130° C. by outside cooling with water. After the addition of thesiloxane has been completed, stirring is continued at 120° to 130° C.for sixteen hours. When the mixture is subsequently tested by theaddition of alcoholic sodium hydroxide, Si-bonded hydrogen is no longerreleased.

After distilling off the toluene and excess allyl succinic acid ester atabout 16 mbar, about 100 percent yield based on theoretical is obtainedin the form of an oil. At -20° C. the oil has a viscosity of 39.4 Pa·s,at 23° C. a viscosity of 1.26 Pa·s and at 140° C. a viscosity of 0.034Pa·s.

In order to determine the oil's resistance to oxidation, 2 g of the oilare placed in an open, inclined test tube having a diameter of 12 mmwhich is heated to 150° C. in the presence of air. Gelling can beobserved only after more than 1000 hours have elapsed. However, when thespecimen has been mixed, prior to heating, with 0.5 percent by weight ofdilauryl thiodipropionate, 0.5 percent by weight of2,6-di-tert-butyl-4-methylphenol and 0.5 percent by weight of4-hydroxy-3,5-di-tert-butylbenzylphosphonic acid monoethyl ester asanti-oxidants, gelling can be observed only after 5000 hours haveelapsed.

The breakdown load of the oil in the 4-ball wear test (1400 rpm, oneminute) is 2200/2400 N (breakdown load=transition into the so-calledwear position, cf. F. Nordmeyer et al., Erdol undKohle-Erdgas-Petrochemie, Vol. 25, 1972, page 200).

The breakdown load for a grease consisting of 2 parts by weight of theoil and 1 part by weight of lithium stearate in the above 4-ball weartest is 1900/2100 N.

EXAMPLE 2

In a one-liter, three-necked flask equipped with a stirrer, a refluxcondenser and a thermometer, 0.1 liter of toluene and 128 g of atrimethylsiloxy end-blocked organopolysiloxane having on the average 8dimethylsiloxane and 8 methylhydrogensiloxane units per molecule, 30 gof allyl succinic acid dimethyl ester and 20 mg of trimethylene platinumdipyridinedichloride are mixed and heated to 115° C. with constantagitation. An additional 160 g of allyl succinic acid dimethyl ester isthen added dropwise through the reflux condenser to the heated mixture.After stirring for an additional 12 hours at 120° to 125° C., anadditional 30 g of allyl succinic acid dimethyl ester is added and thereactants are heated between 120° and 125° C. for an additional 7 hours.When a sample of the mixture is tested by the addition of alcoholicsodium hydroxide, Si-bonded hydrogen is no longer released.

After distilling off the toluene and excess allyl succinic acid ester,280 g of an oil is obtained. The oil has a viscosity of 1.02 Pa·s at 23°C. and 0.023 Pa·s at 140° C.

When the oxidation resistance test described in Example 1 is repeated,gelling is observed after approximately 1500 hours in the absence ofanti-oxidants.

The breakdown load of the oil in a 4-ball wear test, is 900/1200 N.

EXAMPLE 3

In a 1-liter 3-necked flask equipped with a stirrer, reflux condenserand thermometer, 0.1 liter of toluene, 100 g of a trimethylsiloxyend-blocked organopolysiloxane having on the average 10 dimethylsiloxaneand 5 methylhydrogensiloxane units per molecule, 30 g of allyl succinicacid di-(2,2-dimethylpentyl)ester and 20 mg of trimethylene platinumdipyridinedichloride are mixed and heated to 115° C. During agitation,an additional 130 g of the allyl succinic acid ester is added dropwisethrough the reflux condenser. After an additional 12 hours of stirringat a temperature of from 120° and 125° C., an additional 20 g of theallyl succinic acid ester is added and agitation is continued foranother 7 hours at 120° to 125° C.

After distilling off the toluene and excess allyl succinic acid ester,225 g of an oil are obtained. The oil has a viscosity of 77 Pa·s at -20°C., of 1.38 Pa·s at 23° C. and 0.025 Pa·s at 140° C.

When the oxidation-resistance test described in Example 1 is repeated inthe absence of antioxidants, gelling after 500 hours is observed.However, when the sample is mixed prior to heating with 0.5 weightpercent of dilauryl thiodipropionate, 0.5 weight percent ofpentaerythrityltetrakis-3-(3,5-di-tert-butyl-4-hydroxylphenyl)-propionateand 0.5 weight percent of 4-hydroxy-3,5-di-tert-butyl-benzyl-phosphonicacid monoethyl ester, gelling is observed after over 3000 hours.

EXAMPLE 4

A mixture containing 180 g of allyl succinicacid-di-(2,2-dimethyl-3-phenylpropyl) ester, 50 g of toluene and 20 mgof trimethylene platinum dipyridine-dichloride is heated to about 100°C. To the heated mixture is added dropwise with constant agitation andover a period of 30 minutes, 24 g of 1,1,3,3-tetra-methyldisiloxane,dissolved in 50 ml of toluene. Subsequently the temperature ismaintained at 110° to 120° C. for 15 hours. When alcoholic sodiumhydroxide is then added to a sample of the mixture, Si-bonded hydrogenis no longer released.

After distilling off the toluene and excess allyl succinic acid ester,150 g of an oil having a viscosity of 15 Pa.s at 23° C. are obtained.

When the oxidation-resistance test described in Example 1 is conductedin the absence of antioxidants, gelling is observed after 5000 hourshave elapsed.

In the 4-ball wear test described in Example 1, the breakdown load ofthe oil is 800/1000 N.

EXAMPLE 5

A mixture consisting of 200 g of a trimethylsiloxy end-blockedorganopolysiloxane having on the average 17 dimethylsiloxane and 17methylhydrogensiloxane units per molecule, 240 ml of anhydrousdi-n-butyl ether, 450 g of allyl succinic acid di-n-butyl ester and 0.5g of activated carbon coated with 5 weight percent based on the weightof the carbon, of metallic rhodium, are heated for 18 hours at 140° C.under constant agitation. Most of the dibutyl ester is then distilledoff at about 16 mbar and the residue is then stirred for an additional18 hours at 140° C. After the catalyst has been filtered off, theremaining dibutyl ether and the excess allyl succinic acid ester aredistilled off at about 1 mbar. The residue represents a yield of about95 percent of theoretical in the form of an oil which has a viscosity of3.4 Pa·s at 23° C.

The breakdown load of the oil in the 4-ball wear test referred to inExample 1 is 1200/1400 N.

In the 4-ball wear test described in Example 1, the breakdown load ofgrease containing 150 parts of the oil and 56 parts ofpolytetrafluoroethylene is 1800/2000 N.

The polytetrafluoroethylene used in this example is available under theregistered trakemark "Hostaflon TF 9205", and has an average molecularweight of from 35,000 to 100,000. The product's average particle size isfrom 5 to 7 microns.

EXAMPLE 6

A mixture containing 150 g of toluene, 210 g of a trimethylsiloxyend-blocked organopolysiloxane such as described in Example 3, 30 g ofallyl succinic acid-di-n-butyl ester and 20 mg trimethylene platinumdipyridine-dichloride is heated to 120° C. Within a period of one hourand under constant agitation 270 g of allyl succinic acid di-n-butylester is added to the heated mixture. After stirring has been continuedfor another 10 hours at 125° to 130° C., an additional 50 g of allylsuccinic acid dibutyl ester and 10 mg of the above mentioned platinumcompound are added and then heating is continued at 130° to 135° C. foran additional 18 hours.

After distilling off the toluene and excess allyl succinic acid ester,410 g of oil are obtained. The oil has a viscosity of 2.83 Pa˜s at -20°C., 0.335 Pa·s at 23° C. and 0.017 Pa·s at 140° C.

When the oxidation resistance test described in Example 1 is carried outin the absence of antioxidants, gelling is observed after 1500 hours.However, when the antioxidants described in Example 3 are used in theamounts indicated in the Example, gelling is observed after 3800 hourshave elapsed.

EXAMPLE 7

A mixture containing 200 g of dimethylpolysiloxane havingdimethylhydrogensiloxy terminal units, which has an average of 32dimethylsiloxane units per molecule, 100 ml of toluene and about 10 mgof trimethylplatinum dipyridine-dichloride is heated to 115° to 120° C.About 55 g of allyl succinic acid di-n-butyl ester are added dropwise tosaid heated mixture with constant agitation. After the ester additionhas been completed, stirring is continued for an additional 5 hours at115° to 120° C.

After distilling off the toluene and excess allyl succinic acid ester,essentially a 100 percent yield based on theory is obtained in the formof an oil. After filtering the oil through Fuller's earth, it has aviscosity of 0.222 Pa·s at -20° C., 0.047 Pa·s at 23° C. and 0.015 Pa·sat 80° C.

When the oxidation-resistance test described in Example 1 is performedin the absence of antioxidants, gelling is observed after 2000 hourshave elapsed.

In the 4-ball wear test described in Example 1, the breakdown load ofthe oil is 500/700 N.

EXAMPLE 8

A mixture consisting of 280 g of trimethylsiloxy end-blockorganopolysiloxane having on the average 15 phenylmethylsiloxane unitsand 15 methylhydrogensiloxane units per molecule, 500 g of allylsuccinic acid di-n-butyl ester and 1 g of activated carbon coated with 1weight percent based on the weight of carbon of metalic rhodium, isheated for 7 hours to 150° C. with constant stirring and then stirringis continued at the same temperature for an additional 7 hours. Then 0.3g of the activated carbon rhodium mixture described in Example 5 isadded and stirring is continued for an additional 12 hours at 150° C.After the catalyst has been filtered off, excess allyl succinic acidester is distilled off at about 1 mbar. The yield is about 55 percent oftheory and consists of an oily residue which has a viscosity of 740 Pa·sat -20° C., 3.2 Pa·s at 23° C. and of 0.356 Pa·s at 80° C.

When 0.1 weight percent of phenothiazine is added to the oil and theresultant composition is subjected to the oxidation resistance testdescribed in Example 1, gelling is observed after about 400 hours.

The breakdown load of the oil in the 4-ball wear test described inExample 1 is 1400/1500 N.

EXAMPLE 9

A mixture containing 400 g of anhydrous di-n-butyl ether, 405 g of allylsuccinic acid di-n-butyl ester and 1 g of activated carbon coated with 1weight percent based on the weight of the carbon, of metallic rhodium,is heated to 130° C. Within 30 minutes and with constant agitation, 180g of a trimethylsiloxy end-blocked methylhydrogensiloxane containing onthe average 35 methylhydrogensiloxane units per molecule are added tothe mixture. After 1 hour has elapsed, 4-methylpentene-1 is added atsuch a rate that the temperature does not drop below 130° C. After 60hours the unreacted 4-methylpentene-1 and dibutyl ether are distilledoff and fresh 4-methylpentene-1 is added. The total amount of4-methylpentene-1 added is about 250 g. Stirring is continued at 130° to140° C. for an additional 30 hours. After the catalyst has been filteredoff, low-boiling constituents are distilled from the reaction mixture ata temperature of 170° C. and at 0.5 mbar. An oil is recovered which is95 percent of theory and has a viscosity of 93 Pa·s at -20° C., 2.5 Pa·sat 23° C. and of 0.34 Pa·s at 80° C.

When antioxidants are omitted, gelling was observed after about 300hours when the oxidation-resistance test described in Example 1 wasperformed.

The breakdown load of the oil in the 4-ball wear test described inExample 1 was 1800/1900 N.

EXAMPLE 10

A mixture containing 100 g of toluene, 35 g of a trimethylsiloxyend-blocked methylhydrogenpolysiloxane having 30 methylhydrogensiloxaneunits per molecule, and about 30 mg of trimethylene platinumdipyridine-dichloride was heated to 110° to 115° C. About 250 g of allylsuccinic acid-di-(2-methoxyethyl) ester was added dropwise whilestirring to the heated mixture. After the addition of the ester had beencompleted, stirring was continued at 120° to 130° C. for an additional36 hours.

After distilling off the toluene and excess allyl succinic acid ester,an oil was recovered in essentially 100 percent yield based on theory.

When the antioxidants described in Example 3 were used in the quantitiesshown in the Example, the oxidation-resistance test described in Example1 indicated that gelling occurred only after about 3000 hours.

The breakdown load of the oil in the 4-ball wear test described inExample 1 was over 2000 N.

EXAMPLE 11

The procedure described in Example 10 was repeated, except that the samemolar quantity of allyl succinic acid di-n-butyl ester is substitutedfor the allyl succinic acid di-(2-methoxyethyl) ester.

EXAMPLE 12

The procedure described in Example 10 is repeated, except that the samemolar quantity of allyl succinic acid di-methyl ester is substituted forthe allyl succinic acid di-(2-methoxyethyl) ester.

COMPARISON EXAMPLE V₁

The procedure described in Example 10 is repeated, except that the samemolar quantity of undec-10-en-acid-n-butyl ester is substituted for theallyl succinic acid di-(2-methoxyethyl) ester.

COMPARISON EXAMPLE V₂

The procedure described in Example 10 is repeated, except that the samemolar quantity of allyl acetic acid-n-butyl ester is substituted for theallyl succinic acid di-(2-methoxyethyl) ester.

COMPARISON EXAMPLE V₃

The procedure described in Example 10 is repeated, except that the samemolar quantity of vinyl acetic acid-n-butyl ester is substituted for theallyl succinic acid di-(2-methoxyethyl) ester.

COMPARISON EXAMPLE V₄

The procedure described in Example 10 is repeated, except that the samemolar quantity of maleic acid di-n-butyl ester is substituted for theallyl succinic acid di-(2-methoxyethyl) ester.

COMPARISON EXAMPLE V₅

The procedure described in Example 10 is repeated, except that the samemolar quantity of allyloxy acetic acid-n-butyl ester is substituted forthe allyl succinic acid di-(2-methoxyethyl) ester.

The oils obtained in accordance with Examples 11 and 12 as well as withComparison Examples V₁ through V₅ were tested for their resistance tooxidation in accordance with the procedure described in Example 1. Thefollowing Table shows the results obtained in the presence and absenceof the antioxidants cited in Example 3.

                  TABLE                                                           ______________________________________                                                         Number of hours after which                                                   gelling is observed                                          Exam-                  Without anti-                                                                            with anti-                                  ple   Ester            oxidants   oxidants                                    ______________________________________                                        11    Allyl succinic acid-di-n-                                                     butyl ester      200-400    600-800                                     12    Allyl succinic acid-di-                                                       methyl ester     (*)        over 3500                                   V.sub.1                                                                             Undecenic acid butyl                                                          ester            less than 20                                                                             100-200                                     V.sub.2                                                                             Allyl acetic acid butyl                                                       ester            less than 20                                                                             50                                          V.sub.3                                                                             Vinyl acetic acid butyl                                                       ester            40-60      200-300                                     V.sub.4                                                                             Maleic acid dibutyl                                                           ester            20-50      less than 100                               V.sub.5                                                                             Allyloxy acetic acid                                                          butyl ester      undetermined                                                                             less than 100                               ______________________________________                                         (*) Not determined, compare with Example 2                               

EXAMPLE 13

A solution containing 136 g of trichlorosilane in 150 g of toluene isheated to 60° C. About 300 g of allyl succinic acid di-n-butyl ester and100 mg of H₂ PtCl₆.6H₂ O which has previously been dissolved in 0.4 mlof cyclohexanone and mixed with the ester are added to the heatedsolution. The addition is made dropwise and the temperature is allowedto increase to 85° C. Agitation is continued at 94° to 100° C. for anadditional 6 hours. The solution containing thetrichlorosilylpropylsuccinic acid di-n-butyl ester is then mixed with117 g of trimethylchlorosilane. About 100 g of water are added dropwisewith constant agitation to the silane mixture while the temperature ismaintained between about 30° and 40° C. After 3 morehours of agitation,the excess water is distilled off as an azeotrope. The anhydroussolution is then mixed with 3 g of anhydrous, FeCl₃ and stirred for 4hours at between 40° and 50° C., then mixed with 100 g of butanol andheated for 2 hours under reflux while the water generated is removed bymeans of a Dean-Stark trap. The FeCl₃ is then decomposed by the additionof NaHCO₃ and stirred for another 2 hours after it has been mixed with200 ml of water. After distilling off the volatile components at 170° C.at 0.5 mbar, 330 g of an oil having a viscosity of 0.043 Pa·s at 80° C.and 0.012 Pa·s at 140° C. is obtained.

In the 4-ball breakdown test described in Example 1, the breakdown loadof the oil is 1700/1900/N.

EXAMPLE 14

A mixture containing 90 g of a trimethylsiloxy end-blockedmethylhydrogenpolysiloxane having on the average 10methylhydrogensiloxane units per molecule, and 150 ml of toluene and 20mg of bis-(gamma-picoline)-platinum dichloride is heated to 110° to 120°C. Over a period of about 30 minutes and under constant agitation, 350 gof allyl succinic acid diethyl ester is added to the heated mixture.When the addition of the ester has been completed, agitation at 135° C.is continued for an additional 8 hours.

After distilling off the excess allyl succinic acid ester, 333 g of anoil having a viscosity of 0.96 Pa·s at 23° C. and 0.081 Pa·s at 80° C.are recovered.

In the 4-ball wear test described in Example 1, the breakdown load ofthe oil is 1300/1500 N.

The bis-(gamma-picoline)-platinum dichloride used in Example 14 isprepared by the following procedure: About 20 g (48 mMol) of K₂ PtCl₄are dissolved in 150 ml of water, then mixed with 7.5 g (96 mMol) ofgamma-picoline and then heated to 70° C. while being agitated. A lightyellow precipitate is formed, which after cooling is filtered and thefilter residue washed with water and dried under a pressure of 1 mbar.About 15 g, i.e. 69 percent by weight based on the weight of K₂ PtCl₄,of bis-(gamma-picoline)-platinum dichloride are obtained.

EXAMPLE 15

A mixture containing 140 g of allyl succinic acid anhydride, 150 g oftoluene and 0.2 g of H₂ PtCl₆.6H₂ O is heated to 110° C. Over a periodof 3 hours and with constant stirring, a solution containing 150 g oftrichlorosilane in 150 g toluene is added to the heated mixture. Afterstirring for an additional 2 hours at 115° C., the excesstrichlorosilane and about 100 g of toluene are removed by distillation.About 140 g of ethanol, containing 6 percent by weight of water based onthe total weight of water and ethanol, are added dropwise to theresidue. After 4 hours at 40° to 45° C., hydrogen chloride is no longerevolved. The solution obtained is first mixed with 110 g oftrimethylchlorosilane and then with 150 g of ethanol and stirred for 3hours at 50° C.

The mixture obtained is then hydrolyzed by the addition of water and thehydrolyzate is washed until it is free of acid. After distilling themixture at a temperature of 170° C. and at 0.5 mbar, to remove thevolatile components, about 270 g of an oil having a viscosity of 30 Pa·sat -20° C., 0.398 Pa·s at 23° C. and of 0.028 Pa·s at 80° C. isrecovered.

EXAMPLE 16

In a 1-liter, 3-necked flask which is equipped with a stirrer, refluxcondenser and thermometer, 100 g of di-n-butyl ether and 210 g of atrimethylsiloxy end-blocked organopolysiloxane having on the average 165dimethylsiloxane and 30 methylhydrogensiloxane units per molecule, areheated to 150° C. About 0.1 g of H₂ PtCl₆.6H₂ O is dissolved in 1.5 mlof isopropanol and mixed with 160 g of allyl succinic acid di-n-butylester. This mixture is then added to the polysiloxane solution throughthe reflux condenser and stirred for an additional 7 hours at 150° C. Ata pressure of about 20 mbar, the solvents and the excess allyl succinicacid di-n-butyl ester are distilled off. Finally, at a pressure of 0.5mbar, any residual volatile compounds are distilled off at a temperatureof 190° C.

Approximately 300 g of an oil having a viscosity of 0.121 Pa·s at 140°C., 2.26 Pa·s at 23° C. and 260 Pa·s at -45° C. are recovered.

In the 4-ball wear test described in Example 1, the breakdown load ofthe coil is 400/600 N.

What is claimed is:
 1. Organosiloxanes having SiC-bonded ester groupswhich contain at least one unit of the formula

    ROOCCH.sub.2 CH(COOR)CH.sub.2 CHR'CH.sub.2 Si(CH.sub.3).sub.a O.sub.3-a/2

in which R is selected from the group consisting of monovalenthydrocarbon radicals having from 1 to 12 carbon atoms which are free ofaliphatic unsaturation and monovalent hydrocarbon radicals having oneether oxygen atom, R' is selected from the group consisting of hydrogenand CH₃ radical and a is 0, 1 or
 2. 2. The organosiloxanes of claim 1,wherein the remaining units are those of the formula:

    R".sub.b SiO.sub.4-b/2

in which R" is selected from the group consisting of monovalenthydrocarbon radicals and halogenated monovalent hydrocarbon radicalshaving from 1 to 10 carbon atoms which are free of aliphaticunsaturation and b is 0, 1, 2 or 3; in which the organosiloxanes containa total of 2 to 300 silicon atoms per molecule.
 3. A process forpreparing the organosiloxanes of claim 1 which comprises reacting adiester of the formula

    ROOCCH.sub.2 CH(COOR)CH.sub.2 CR'═CH.sub.2

in which R is selected from the group consisting of monovalenthydrocarbon radicals having from 1 to 12 carbon atoms which are free ofaliphatic unsaturation and monovalent hydrocarbon radicals having oneether oxygen atom and R' is selected from the group consisting ofhydrogen and CH₃, with an organosiloxane having Si-bonded hydrogen inthe presence of a catalyst which promotes the addition of Si-bondedhydrogen to an aliphatic multiple bond.
 4. The process of claim 3,wherein the diester is a diester of allyl succinic acid.
 5. The processof claim 3, wherein the diester is a diester of methallyl succinic acid.6. The process of claim 3, wherein the diester is a mixture containing adiester of allyl succinic acid and a diester of methallyl succinic acid.7. The process of claim 3, wherein the reaction is conducted at atemperature of from 18° to 180° C.